Estudo do comportamento do sinal eletromiográfico de superfície em atividades subaquáticas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

In this doctoral thesis in Electrical Engineering, methodologies for acquisition, processing and interpretation of the surface electromyographic (EMG) signals in underwater environments were developed. The effect of the aqueous environment on the electromyographic variables was studied as well. Four experiments involving both the abductor pollicis brevis and the biceps brachii muscles were performed in aerial and in underwater conditions. In the first experiment, the repeatability of a protocol involving isometric contractions of the abductor pollicis brevis muscle was evaluated, and the results showed that the protocol developed has a good repeatability. This protocol was used in the second experiment, whose goal was to evaluate if there are differences in the electromyographic variables (amplitude and spectral parameters) measure in air or underwater. The results showed no significant differences between the electromyographic variables in the two environments. In the third experiment, the electromyographic signal was measured in the biceps brachii, in both aerial and underwater environments for both total body immersion and only the immersion of the limb. The experiment showed significant differences between the electromyographic variables measured in the two environments. However, when the effect of the buoyancy force exerted by the water on the arm was compensated for, no significant differences were found. This experiment showed that decreases in EMG variables measured in water are just due to the buoyancy effects and that, once these effects are counteracted, there are no differences between the electromyographic variables measured in the two environments. In the fourth experiment the electromyographic signal was measured in the biceps brachii, during dynamic contractions, for both air and aqueous environments. Several electromyographic measurements (average rectified value, mean freque ncy and conduction velocity) were studied, and the results showed that, if the effects of water temperature and of buoyancy and dragging forces of the water are properly counteracted, then there are no significant differences in the electromyographic measurements. These results are important, since it settles the fact that there is no effect of water on the electromyographic signals other than the buoyancy and dragging forces. The work is also important because it presents different techniques for dealing with and for analyzing surface EMG signals measured in underwater environments.

ASSUNTO(S)

arranjo linear de eletrodos captação de emg em água emg biomecânica eletromiografia water activities engenharia eletrica sinal de emg surface electromyography linear electrode array

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